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Your favorite FTL Drive


L. Marcus

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I seem to recall four distinct drive types mentioned in Star Hero; Displacement (instant teleportation), Hyperspace (tunneling through an alternate dimension), Probability (some sort of quantum pair synchronization if I understand it) and Warp (distorting space to make it 'smaller'). Depending on the rules that dress each one of those up, I like all of them. The important thing about FTL is that it is down time between Point A and Point B. While there doesn't necessarily need to be anything happening during that interval, there is opportunity for role-playing, adventure, or even just between story background stuff (character advancement, bluebooking or whatnot). In that regard, my least favorite is anything that is near instantaneous. That takes away a narrative tool that I like to employ.

 

For sheer flavor, I prefer Displacement drives that have to 'spin up' over time and can only be activated when far enough outside of a planetary gravity well. This fits the extended time between points both coming and going. I prefer short-range jumps of less than a dozen light years. I also prefer the Star Frontiers mechanic of having to overhaul drives between jumps or risk the jump drive mis-jumping to someplace that the navigator had not intended to go. 

 

This is a very bare bones write up. For a setting I am tinkering with, this would go into a Multipower that governs all of the ships systems. Also, for this setting, making a jump is an extended test that requires a Navigation (Space) and System Operations (Navigation) roll. There are many ways to misjump in this setting from the engine, to not plotting the correct course, to entering a wrong digit when preparing for the jump. Not to worry though, I tend to have adventures waiting in every little dark nook and cranny of my settings.  :eg:

 

Displacement Drive:  Teleportation 3m, x4 Noncombat, Reduced Endurance (0 END; +1/2), MegaScale (1m = 1 lightyear; +4 1/4) (46 Active Points); Extra Time (6 Hours, -3 1/2), Degrading: Begins with an Activation roll of 18-. Each successive jump reduces the Activation roll by 1 for every (portion of) three light years jumped. A failed activation roll means the drive did not activate. An 18- roll means that the drive misjumped. Engine Maintenance can restore the Activation roll up to the engineer's skill rating in the field or fully at a star base. (-1 1/2)

Active Cost: 46

Real Cost: 8 (or 2v for a multipower slot)

END Cost: 0

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I love B5's Hyperspace drives. You need an active pilot while going from place to place. To navigate the dimensional flow and keep heading toward the "beacon" I love that with the use of stargates (Big Stationary FTL Drives that open a hyperspacial gateway to any ship)

Also, a similar drive would be Andromeda's Slipstream Drive. Where a good roll can make a trip that usually takes weeks, take days. Basically a Hyperspace drive that relies on a good Slipstream Piloting/Navigation roll. IIRC a bad piloting roll can cause you to end up short of one's destination.

Traveller's Jump drives hold a place in my heart due to it being my first SciFi RPG. It's a Displacement Drive that takes a week to go up to the drive's rating (from 1 - 6 parsecs per jump). Ships only keep enough fuel for one Jump. Has to be performed ~100 diameters outside of a gravity well, or you could end up somewhere else.

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I've been bouncing around a setting where several systems are used to move ships about.

 

1) Gravity Drive: This is a reactionless drive that can provide very high acceleration.  Velocity generated by the Gravity Drive is called "True Velocity".  For this reason, the Gravity drive is often referred to as the True Drive or T Drive.

 

2) Warp Field Generator: This is a device that warps space ahead of the ship (and un-warps it behind) effectively increasing a ships speed by a factor of about 250, The WFG can only work on space relatively near the ship and takes a small amount of time to do the warping, so anything moving faster than about 0.001C outruns the effect.  This means that a warping ship is limited to about a quarter of lightspeed.   When warping space, a bit of 'bend' can be worked in, allowing a ship to turn.  Even though it is not really a drive, people often call it the Warp Drive.

 

3) Hyperspace Shunt: This device displaces a ship 'upward' to a congruent parallel dimension where things are about 4x closer together. Each time it is recharged and used again, the ship can move to an even higher level of hyperspace where things are 4x closer again.   Hyper space levels are named for Greek letters.  The 4x level is "Alpha", 16x in "Beta", 64x is "Delta" and so on. Even after it is discharged, the shunt requires a (relative) trickle of power to keep the ship in hyperspace.   If the power is not delivered, or the shunt is damaged, the ship will crash back into normal space, most likely sustaining damage or possibly being destroyed in the process.   A ship can make a jump of more than one level at a time, but it is hard on the ship and more difficult for the pilot.    The shunt will not operate in the vicinity of large masses.  For a Sol sized star, this 'vicinity' extends out to the orbit of Neptune, about.

 

 

More to come....

4) Hyperspace Curvature:  

5) Why all the complications?

6) Applicable skills

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In the only sci-fi campaign where I had a voice in the universe-building (as opposed to buying source material and using it as given), I use a "jump" drive, which is instantaneous for the ship and its occupants, but is extraordinarily disorienting to any mentality that experiences the jump while conscious (so most entities take a jump while sedated). This is the FTL drive mode in C J Cherryh's stories. My partner GM insisted on that flavor, though I was free to make up whatever fake physics I wanted.

 

... Which I did, of course, at far greater length than is needed for a game. I started by asserting the usual lethal consequences of activating the jump drive while in space with greater-than-tolerable curvature (which usually means too close to a stellar or planetary mass, but there are interesting exceptions to that). It also means you don't care about the actual contents of interstellar space, unless there happens to be a free-floating planet or other dark compact object near the geodesic (line of travel) you're following. We never invoked that problem though I did keep it as an ace in the hole for Evil GM purposes.

 

This finessed away the possibility of FTL ship-to-ship combat, but it means staying with known relativistic mechanics for in-system maneuvers and any ship-to-ship combat. This means the ship drives have make to kinetic energy at rates larger than planet Earth in CE 2010, that is, a ship drive has to have power of 10^15 W or greater. Some consequences of this can be handwaved away with mostly neutrino exhaust. Others cannot: you can accelerate small masses (has to be big enough to install a drive unit, which I declared to be a minimum of 5 tons or so) to relativistic speeds and you have a world-killing weapons system. There are ways to handle this, too.

 

Before I go much further into tl;dr land, I'll stop here.

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The relativistic weapons thing is something I have contemplated but have no real idea how to handle. If my Displacement (which is really just a fancy term for Jump) drives require that the drive be away from gravity wells, it gives time for an incoming vessel or construct to potentially accelerate to very high speeds. Usually it is a staple of the space opera genre not to have those sorts of weapons routinely used, but it always lies as a possibility that something large enough can be jumped in and sent accelerating right into a planet, moon or space station. I imagine fuel or reaction mass could be a limiter, but in a reactionless drive, rubber science, setting that is one thing that is still present.

 

The short version of that is, I would be interested in hearing your methods of handling those relativistic speed, world-killing weapons systems.

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I prefer the smoots drive from the old Marvel series Open Space. (Something similar is used in the Flandry universe). It's a teleport drive, but only one smoot at a time - the distance across of a hydrogen atom. To generate apparent FTL speed, you just make a lot of jumps very, very fast - make your drive fast enough and your ship seems to be moving through space faster than light, in normal space but with no acceleration or velocity. Space to space combat is impossible in Open Space - the outmatched ship(s) just turn away and they're instantly half a light year from you.

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The short version of that is, I would be interested in hearing your methods of handling those relativistic speed, world-killing weapons systems.

Like the smoots drive I try to think of FTL methods that either don't impart momentum to the spacecraft or don't allow it to interact with the 'real' universe. Teleportation is one method, though you have to account for the use of it as a weapon in other ways (e.g. the transporter effect). Warp drives can work as well, since it is space that is 'moving' and not the craft, though again you have to figure out why the field itself cannot be used as a weapon.

 

I'm also fond of fixed wormholes/stargates as a combination FTL method and plot point.

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I don't know if there is a RPG setting that uses something similar but the jump drive tech specific to the Mote In God's Eye universe (Larry Niven & Jerry Pournelle) is an interesting one. Ship's can only activate their drives at very specific coordinates in the outer reaches of a star system. Once activated, they are instantly transported to a similar coordinate in another star system. Some stars have 10+ jump points and others only 1. The book's story focuses on a system with just 1 in a very special place (inside of a red giant) and the shield tech required to survive the trip.

 

HM

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What I did: Jumps can only be done outside of gravity wells. The same device, however, can provide enough thrust to serve as a "neutrino rocket" inside the gravity wells.

 

How you control this: all star systems occupied by every starfaring race are heavily fortified. Activating a drive in neutrino-rocket mode is screamingly obvious to anyone with a jump drive within a star system (for hundreds of AU's away from the drive being on). If you activate that drive without permission in fortified space, then dozens, perhaps hundreds, of idling lurking kinetic-kill rockets disguised as meteoroids activate and home in on the offending active drive. And under no circumstances are starfaring vessels permitted in the inner parts of the star system (where the inhabited planets are). There are enough of these lurking defense rockets so widely spread around the star system that no plausible attacker will be able to get a projectile hit on a planet.

 

As for attack from outsystem, you come out of jump far away from the star, when the gravity exceeds some pretty weak value (IIRC four our Solar System it was about 40 AUs out from the Sun). In general sentients always are sedated during jump, and you don't know very well where you're coming out of jump. I can go into that at more length, but it's heavy geekdom again.

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Too many drive systems to choose from to pick a absolute favoirite. I am partial towads Sword of the Stars 1+2, because each race thier has thier own unqiue drive. Not that easy to do with 7 different species!

I guess we can classify drives by the following characteristica:

Speed of Movement: Instantanous, Absolute fixed time (Traveler), Pathspecific fixed time (Star Wars Hyperdrive), Fast, Normal, Slow. The last 3 are in relation to other sets of drives that a similarily measured.

Selection of Target: Free Selection (inlcuding stuff in deep space), Gravitational Targetting (only towards Masses like planets or even solar systems), Other Stellar Targetting (lk only planets with abundance of life/psionic power/the force/magic), custom build Gate/Beacon only (so you have to get there another way, maybe the hard way)

Selection of Origin: Free Selection (park in deep space), Stealler Source (only close from a Planet/system), prebould Gate/beacon only

Freedom of Useability: Freely useable by everyone you let it use (stargates or hyperlane networks), Ship requirements (a drive section), Ship+Path requirements (you need a drive and the prebuild gates/hyperlanes)

Effiency factors: Faster/slower with many ships nearby. Faster/Slower around gravity wells.

STL/IP use: If the drive can or cannot be used as STL drive or interplanetary drive too.

Communication use: If the drives technology can be used to transmit data, other then via courier ships/bouys

Reachability/Reactiontime of ship in transit: If you can reach the ships and if they can change course mid flight

Environmental Impact: If the drive causes damage to Spacetime, it's medium, source or target system when in use.

Freedom of reuse: Is there a cooldown before you can jump out again? Limited fuel that only allows 2-4 Jumps without refuelling?

Special Drive ships: Does every ship in the fleet need the drive, or only a few that can take the others along? (In addition to actuall carriers)

Fleet interaction mid Transit: Can ships in a fleet physically interact/dock while zipping around?

Safety of the Medium: Are there hostile inhabitants in the Medium? Can others using the same medium intercept you?

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I'm interested, but if you start throwing strange arcane symbols (mathematical equations), my brain might go into sparky, explosive, Star Trek console mode.

Assuming it's a single star with planets and the planets are of negligible mass compared to the star, then your ship will come out of jump somewhere on the "front" hemisphere centered on the target star as seen by the ship at the instant of jump. For a 1 solar mass star that hemisphere is 40 AU in radius and it scales directly with mass for single stars.

 

The jump follows the geodesic on which your ship is headed when you activate the jump. "Geodesic" is the path that light follows through space ... a straight line in truly empty space, slightly warped by gravity of the rest of the Galaxy in real life. So operationally, you have a telescope fixed facing forward on the central axis of your ship (making sure your momentum vector really is along that axis). Point along that and viola! you where where you see. But...

 

Now, for a star at the modest distance of 10 parsecs, the 40-AU radius target disk (your view of where your jump should end) is 8 arc seconds in angular diameter. At 20 parsecs it's half that. At 40 parsecs it's 2 arc seconds in diameter.

 

Those are small angles. You need a telecope to resolve them (see them as more than just a dot). If all you had was that on-axis telescope to do your heading, you would run a scarily high chance of not having your pointing good enough ... which means your ship stays in jump, moving along that geodesic until it hits some other point with a high enough gravity to nudge you out of jump. That could be very, very far away. If you're unlucky enough, you may be going so far you end up much earlier in time, back when the Universe was denser and the gravity field that much stronger. That's a one-way trip.

 

In a mature fully occupied system, there will be lots of navigation aids -- multiple deep radars, trigonometric locating with baselines as big as the star system, extensive astrometric libraries, and computing power to ensure externally that your heading is as good as possible when jump is activated. Much safer. The hard part when exploring is the return trip, if the campaign universe is in the just-starting-interstellar-travel domain which ours was. Then you lean real hard on your telescope. And you will want one at least a meter in aperture, or better, linked to some kind of interferometer array with eight or ten 20-cm telescopes scattered over the leading surface of the ship, some 5 or ten meters wide or more.

 

Then there's other tricks. Stars have individual motions with respect to each other that may be up to a couple hundred km/sec in magnitude, and in general are randomly oriented. Here some handwaving starts, because you're going into the teeth of time-travel paradox. A geodesic is the curve light travels, but the light you are using for your navigation was emitted years ago. By definition you're going to go faster than light. How fast are you moving during jump? If it's really infinitely fast then the star isn't now where you see it to be, and you need to work out where the star is now based on its space motion relative to yours and possibly make corrections to where you jump. If it isn't infinitely fast then it's somewhere between that now location and where you see it to be now.

 

There's also the issue of what happens to your real-space momentum when you emerge from jump. The simplest approach is to say that when jump ends you emerge at zero velocity relative to the gravity source that ended your jump. An alternate approach is to keep the momentum vector you had at the instant of jump, so you emerge from jump with the vector sum of your momentum w/r/t the star you jumped from plus the velocity vector difference between the two stars, which could be as much as a couple hundred km/sec even among nearby stars. We handwaved in a third capacity of the jump drive, that the drive can dump off that momentum difference, but at a rate that meant you had hours of dumping to do on most interstellar jumps. (Going this route makes interstellar attacks even more difficult, which was a reason we made this choice.)

 

I never finished deciding how fast jump is, partly for the where-do-you-point reason, and partly for time travel/causality violation reasons, neither of which I could see easy solutions for. Being as astronomer handicaps me in odd ways, in that I am unwilling to play completely fast and loose with real physics, and grappling with time travel paradoxes is something I didn't want to do.

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Bravo! That is awesome.

 

Regarding the array of telescopes, would it be possible in your campaign for a ship that is returning from exploration to deploy a small drone network to help center the ship on that crucial 2-8 arc second window? Would it help or simply not provide enough of a statistical advantage to be practical?

 

Regarding your background, I have similar issues running campaigns based on Earth in anything akin to a historical setting. I even have a hard time with "real" space that has been mapped out to the point where we have a reasonable understanding of the astronomical "geography" of other solar systems is. I tend to be a little OCD about that sort of thing and get caught up in the minutia of making sure all the real facts are correctly presented. It really overwhelms the fun with stress. For that reason, everything I run is either fantasy land or my own galaxy far far away. One of the reasons I like the Star Frontiers setting so much.

 

With physics, I can play fast and loose with. :)

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One idea that I played around with was having two distinct types of FTL. One kind opened up a portal between two different points in space. It was virtually instantaneous, but it required vast amounts of energy to operate. This limited its use to sector capitals or other important systems. The other was a space-warp drive that could be carried on a ship, but it was much slower (about a light year every couple of days). This meant that the characters could travel halfway across the galaxy in a few hours, but might take weeks to go only a few parsecs.

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I had two FTL options in my last science fiction game setting.

 

The first, and more conventional, FTL was known as a Submersion Drive - it's a hyperspace model where you 'submerge' into a parallel dimension.  The deeper you can submerge (ie the farther away from the 'main' universe you can get) the faster you travel.  The drawback to the drive was that this submersion space was *not* friendly to matter  - a type of submersion radiation cooked humans at about 100 time the speed of light and atomized any known material at around 10,000 times light speed . Other races had different tolerances, most higher than human, so the humans were the first to develop Submersion Jammers that pulled passing ships back to real space.

 

The second, developed by humans, was a Wormhole Generator Drive.  They're fickle, to put it mildly - the wormholes they generate not only move a ship through space but also through time (forward).  The wormholes are very heavily (and somewhat randomly) affected by gravity, as humans learned the hard way - you'll always get where you're going but larger gravity fields increased the time distortion affect dramatically.  A jump from the surface of earth could move you forward anywhere in time from a few days to a few weeks.  A jump from a near orbit of the sun could easily cost you a century.

 

Once humanity figured that out and started jumping from outside the heliopause (where usually a jump would move you forward a few hours to a few days) they found themselves moving from last place in the interstellar races FTL capabilities to first place in a big way.

 

To date no counter to a wormhole incursion has been developed (not for a lack of trying among the galactic community) - the WGD is humanities ace in the hole (so much so that each drive is sealed and is equipped with an AI whose sole purpose for existing is to stop the drives from falling into non-human hands via a nuke at its core, as well as detonate if the host ship becomes inoperable due to damage or running out of fuel).  Military vessels among several races are, however, now equipped with graviton weapons that saturate a forming wormhole (adding years or even decades to any escape attempt, relatively speaking - a scout ship trying to jump back with data about an impending attack is less useful if the attack has been carried out decades before they arrive home).

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Regarding the array of telescopes, would it be possible in your campaign for a ship that is returning from exploration to deploy a small drone network to help center the ship on that crucial 2-8 arc second window? Would it help or simply not provide enough of a statistical advantage to be practical?

In principle, yes. The exoplanet research people would love to have it. It is probably about 25 years away (two 10-year development cycles) once it gets funded again (that was zeroed out back in G W Bush's 2nd term, and has not been popped back up).

 

Regarding your background, I have similar issues running campaigns based on Earth in anything akin to a historical setting. I even have a hard time with "real" space that has been mapped out to the point where we have a reasonable understanding of the astronomical "geography" of other solar systems is. I tend to be a little OCD about that sort of thing and get caught up in the minutia of making sure all the real facts are correctly presented. It really overwhelms the fun with stress. For that reason, everything I run is either fantasy land or my own galaxy far far away. One of the reasons I like the Star Frontiers setting so much.

 

With physics, I can play fast and loose with. :)

The near-now campaign background was something required by my co-GM, and all this was worked on dozen years back. I had the SOTA stellar data available ... and the star I picked out for humanity's first interstellar visit was one that subsequently had a planet found in it. As for the OCD ... umm, yes, I share that; I had just about all the real data I needed. :)

 

We had much fun creating the first starfaring race, too; I have mentioned them before, the intelligent, psionic shrubs, with their partly-uplifted weasel clients and the fungi they can genetically engineer into something new almost overnight, which meant their space vessels and stations had almost literally wooden hulls.

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I don't know if there is a RPG setting that uses something similar but the jump drive tech specific to the Mote In God's Eye universe (Larry Niven & Jerry Pournelle) is an interesting one. Ship's can only activate their drives at very specific coordinates in the outer reaches of a star system. Once activated, they are instantly transported to a similar coordinate in another star system. Some stars have 10+ jump points and others only 1. The book's story focuses on a system with just 1 in a very special place (inside of a red giant) and the shield tech required to survive the trip.

 

HM

 

The Starfire game and the novels based off it had a very similar system.  But the number of "warp points" was usually in the 1-4 range and "blind" (one way) points existed.  Warp points also had varying and limited tonnage capacity as well. 

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In principle, yes. The exoplanet research people would love to have it. It is probably about 25 years away (two 10-year development cycles) once it gets funded again (that was zeroed out back in G W Bush's 2nd term, and has not been popped back up).

 

 

I meant for FTL ships in your campaign. :)

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In the only sci-fi campaign where I had a voice in the universe-building (as opposed to buying source material and using it as given), I use a "jump" drive, which is instantaneous for the ship and its occupants, but is extraordinarily disorienting to any mentality that experiences the jump while conscious (so most entities take a jump while sedated). This is the FTL drive mode in C J Cherryh's stories. My partner GM insisted on that flavor, though I was free to make up whatever fake physics I wanted.

C J Cherryh's FTL drive is pretty definitely not instantaneous. You set your destination course very, very, very, very carefully because your destination's stellar gravity well is what pulls you back into real space. Then you set up your IV and drug yourself senseless because most races can't deal with FTL conditions. I recall from the Chanur books that getting your ship infested with vermin that can breed and move about in FTL was really bad.

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For the universe of my Planetary Romance campaign, I postulated three modes of FTL. The planoform drive (name stolen from Cordwainer Smith) and linoform drives were forms of warp drive. They worked by expanding the "hidden dimensions" of 11- dimensional space-time postulated by Superstring Theory, then rotating the ship along one or two of those dimensions to leave a plane or line cross-section as sole interface with the wider universe. Within the bubble, the ship travels less than lightspeed; the bubble itself can travel much faster. (And since the 2-dimensional or 1-cimensional cross-section is massless, it can indeed travel no slower than lightspeed.)

 

The two drives differ in their power requirements. The planoform drive is easy to scale up to propel larger masses, but the power consumption rises so rapidly with speed that it's effectively limited to 60x lightspeed. The linoform drive is easily scaled up for higher speeds, but not for ship's mass. So, you can send small ships flitting hundreds of light-years, but moving large numbers of people or large cargoes is limited to planoform speeds. This has various military, political, and economic consequences that would likely be tl;dr.

 

The Enigma Gate is a punctiform drive. Such a drive is not much harder to build than the other two; you just rotate the ship out of all three normal special dimensions, leaving a point section. In this state, the ship is less than a proton's width away from every other point in the universe, and thus can go anywhere instantaneously. Unfortunately, humans and other races have not figured out how to specify where the ship emerges. The Elder Races did so, however, and left the Enigma Gates as a stargate system. Just fly your ship into the Gate while transmitting the access code for your destination and poof, you're there. The enigma consists of how the Gate determines your destination.

 

And time travel? Not so far. Every time a clever physicist thinks of a way to rotate a ship through the temporal dimension and so turn it into a time machine, some other clever physicist finds a flaw and closes the loophole.

 

The same underlying technology also produces deflector beams and shields. Send out a pules of space distortion to throw a missile off course, or create two warps that almost cancel each other out to surround the ship with a bubble of intensely sheared space-time, making it harder to hit and diffusing energy weapons.

 

Dean Shomshak

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